1. Field of the Invention
The present invention relates to a spindle motor and more specifically to a spindle motor for use in a disk drive apparatus.
2. Description of the Related Art
In recent years, in accordance with increased storage density of disks, there has been a demand for disk drive apparatuses, such as hard disk drives, to control rotation of the disks, movement of heads, and so on with high precision. In a known hard disk drive (HDD) disclosed in JP-A 2006-40423, a gas arranged in an interior of the HDD is a low-density gas, such as a helium gas or a hydrogen gas, and the HDD is thereby arranged to achieve a reduction in resistance of the gas against a disk, a head, and so on during rotation of a spindle motor. The reduction in the resistance of the gas against the disk, the head, and so on contributes to reducing vibration of the disk, the head, and so on, enabling highly precise data recording.
Bases of some spindle motors (hereinafter referred to simply as “motors”) installed in HDDs are defined by portions of housings of the HDDs. In the case where the interior of the HDD is filled with a gas such as a helium gas or the like as described in JP-A 2006-40423, the helium gas, for example, which has extremely small molecules, tends to easily leak out of the interior of the HDD to an outside of the HDD. Therefore, in the case where a shaft is fixed in a through hole defined in the base, it is not easy to ensure sufficient sealing of a region in which the base and the shaft are fixed to each other.